Imperial motor an Renualt tokai unfair malpractise towards second hand owners

I purchased a car oct 2017 at imperial motors. The car was up to date with everything according to the financial personel.

It is a 2016 model. I took out a service plan, maintence plan and have insurance with renault. I took my car in for a service in 2018 an now january again. For a check up. Now my husband notice a noise on the car when it revs up to a particular gear. Car was booked in this monday an now today i get a call, saying i must pay a 25% of the fee as the car was penalised 2017 cause it was 3 months late for its service. An it was only serviced oct 2017 when i only purchased the car that month an was serviced automatically. Apparently it should have been done 3months prior.

What are my rights. This should of been picked up prior to all the services if they bring up assessments done before i purchased. I feel this unfair practises as i have been following procedure through and paying for maintence, service an now they want to claim from my insurance which has nothing to do with them.